Electric resistance heating element



A 1932- E. STRANSZKY 1,869,629

v ELECTRIC ,RESISTANCE HEATING ELEMENT Filed May 5, 1928 3 Sheets-Sheet 1 Attornegs Emil e ifanszkg Inventor Aug. 2, 1932. I E. STRANSZKY ELECTRIC RESISTANCE HEATING ELEMENT Filed May 5, 1928 3 Sheets-Sheet 2 f llllllll l| l l l I l I I I,

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E'nzii Stranszkg L I n u e 10.120 1* At tor'negsp 7 Aug. 2, 1932. E. STRANSZKY ELECTRIC RESISTANCE HEATING ELEMENT Filed May 3, 1928 3 Sheets-Sheet Emil fitfanszks 1. .Q1 Inventor f 3 4 Attorneys- Patented Aug. 2,. 1932 UNITED STA EMIL STRANSZKY, OF WARREN, PENNSYLVAN 1A ELECTRIC RESISTANCE HEATING ELEMENT Application filed Kay 3, 1828. Serial No. 274,795.

This invention relates to electric resistance heating devices and has for its object the provision of a new and improved type of metal sheathed heating device. Such devices 8' are of value for heating air, water, space,

sheets, pipes, boilers, pots, kettles, stove tops, vulcanizers, pads and in many other relations. Among the objects of my invention are the provision of metal sheathed heating elements which shall be flexible so as to enable them to be bent or formed for appliing a part of thlsapplication I ave shown certain physical forms of different shapes,

sizes, and constructions wherein my inventive ideasare embodied although it will be understood that these are intended merely to be illustrative of the principles of my idea and not to be exhaustive as to the mode of applying the same to practical use. .Fig. 1

. is. a bottom plan view partly in section of a straight strip heater embodying my improvements; Fig. 2 is an end elevation of the device shown in Fig. 1; Figs. 3 and 4 are end elevations of modified constructions; Fig. 5 is a cross sectional view of another modification; Fig. 6 isa side elevation of the heater shown in Fig. 1; Fig. 7 illustrates a heater of the same construction bent longitudinally; Figs; 8 and 9 are similar views showing a heater of this type bent to annular form; Figs. 10 and '11 are perspective viewsof heating elements containing my improvements and bent transversely in difierent directions; Fig. 12 is an enlarged sectional view of one of my improved "heaters showing/ its internal construction; Fig. 13

is a sectional view corresponding to the line .1313 of Fig. 12

' Fig. 14 is a sectional view corresponding to Fig. 13 but showing a modified form of resistanceelement or web; Fig.

15 is a top plan view of a hot plate containing my improvements; Fig. 16 is a sectional view of another type of hot plate contain-l ingmy invention; Fig. 17 is a detail view showing one mode of handling the web or resistance net which I employ; Fig. 18 is a plan view of another type of resistance net F' g. 19 is a perspective view of a space heater or air heater of the naked wire type employing this resistance element; F ig. 20 is a detail cross sectional view of the device shown in Fig. 19; Fig. 21 is a side elevation of a hot water tank provided with my improved heaters and Fig. 22 is a horizontal sectional view on the line 22 of Fig. 21.

In the performance of my invention I take two flat metal sheets, 1 and 2 and fasten them tightly together at their lateral and longitudinal margins while spacing their body portions apart to provide an internal recess as shown in Figs. 5, 12, 19 and 20. In Figs. 1, 2,6 and 7 the sheet 2 is drawn in dies to produce a suitable recess surrounded by a flat margin over which are folded the lateral margins 3 and end margins 4 of the sheet 1 According to the modification shown in Fig. 3 both sheets are drawn to produce the recess mentioned, their margins being joined along a seam 5 midway between the upper and lower surfaces of the strip thereby produced. In Figs. 4, 5, 8, 9, 10, 11 and 12 the adjacent margins of the two sheets are welded together. In all these cases care is taken that the same be tight.

Inside the recess formed between these sheets I locate a resistance net constructed as generally described and claimed in U. S. Letters Patent of Schniewindt No. 1,031,204 issued July 2, 1912, that is to say: A flexible netted fabric is made having its warp and weft composed, one of metallic resistance wires 9, and the other of flexible, heat-resisting insulating material such as asbestos cords 6, sometimes reenforced by other materials. In the 'case of an elongated strip type of heater the warp and weft may run in either direction, although this may depend to some extent upon the voltage employed and the ease of securing proper resistance conditions with proper size-of wire. In the form of the invention shown in Fi 13 the wires run back and forth transverse y of the length of the strip while the insulating cords run lengthwise thereof; in the form of the invention shown in Fig. 14 the wires run lengthwise and the resistance cords cross-wise. These webs or nets are preferably made in the form of Ion ribbons or hands as illustrated in Fig. 1 and. several as shown at for the particular element in question; however, it is equally within my invention to have each resistance web woven specially for the purpose as shown at Fig. 18 in which event the lnsulating cords may be extended beyond the wires and filling cords 8 of insulating material woven therewith to form ends for handling or fastening. It is also within my invention to employ webs woven tospecial shapes, such as the circular outline illustrated in Fig. 16 and so as to conform to the p casing with which the same is to be used.

In the case of a tightly closed sheath the web is encased and shielded from the adjacent walls b thin, flat sheets 10 of some kind of previous y formed heat-resistant and electrically non-conducting, material such as mica: and the entire space inside the sheath may be taken up by these sheets which is not taken u by the resistance material, as shownin Flg. 5; or a filling or backing of some other heat resistant material can be interposed between the mica and one wall of the casmg as shown at 11 in Fig. 12. In some cases, as when air-heating is desired rather than late-heating, one or more sides of the sheat ing can be cut away more or less completely. Thus in Fig. 5 I have shown one face of the member 2 as completely removed to form a rectangular window 15; and in Figs. 19 and 20 I have shown the sheet 2 as formed with numerous apertures 16 to permit the circulation of air. In the last named case the resistance net is secured in place merely by. the use of narrow brackets 17 suitably notched to receive the edges of the resistance net and insulated therefrom by mica as shown at 18.

The ends of the wires are connected to terminals 20-20 of any suitable type which ass through the metal sheathing and are insulated by washers 21 of fiber, mica, or the like. These terminals can be located at opposite ends if desired as shown in Figs. 1 and P 13, or at the same end asshown in Fig.14; and when desired'it is also permissible to employ additional terminals as indicated at 22 in Fig. 14 to enable the resistance net to be used in sections.

Asbestos cord is, of course, naturally soft I and flexible; but at the ends of the net, or at the wires points adjacent to the terminals, or alon the severed edgeswhere it is deslrable to eep rom becoming disarranged, it 1s often convenient to harden or stiffen the same, which can readily be done by the addition of certain chemical solutions, such as a solution of sodium silicate or a mixture of boric acid, 6 parts; silicate of soda, 3 parts, Klingenberg clay 1 part; water sufiicient to facilitate application. I prefer the latter ingredients inas much as the reaction with the asbestos produces a substance which is not only tenaciously unyielding but has a higher melting point than is produced by the action of the sodium silicate alone although the-latter is adequate for many uses. It is also possible to treat the entire surface ofthe resistance element in this manner, turning that which was-previously soft and flexible into a stiff and rigid sheet. This procedure also enables the use of substances other than asbestos, by impregnating a vegetable cord with a suitable mineral either before or after weaving, and subsequently treating the same to volatile or combustible material, leaving only the heat-resisting substance. These sheathed resistance elements can with equal facility be made of any desired size since the net is merely woven on a kind of loom which can be adjusted toany dimension required, and the resulting fabric is of such nature as to retain its shape and the position of its elements throughout the necessary handling. For example, with this construction it is easy to make a hot plate of the type shown in'Fig. 15 which may have a dimension of several feet in each direction, as readily as a strip of the type shown in Fig. 1 which may be only an inch wide and several feet long. After the resistance net has been properly ensheathed, the sheath can be bent sidewise or crosswise as desired to fit an surface to which it is to be applied, as indicated in Figs. 7 to 11 inclusive. Thus in Figs. 21 and 22 I have shown two of my improved elements applied to the exterior of a common galvanized iron hot water tank 25. Each of the elements is bent longitudinally to emroduce a solid mass. When a vegetable cord is used the first heating serves todrive off all brace the tank and is clamped thereto by an I encircling metal hoop 26 whose ends are drawn together by a suitable bolt 27. Each hoop is formed near each end with an aperture 28 to accommodate the terminal connection 20 with which the element is sup lied,

and the clamping parts and termina s are referably housed inside a hollow casing 29 bolted to the outer surfaces of the hoops. practice, of course, the hoops and units and tank are all covered with a jacket or bagging of heat insulating material. The provision of two heating units enables part or all of the water in the tank to be heated according as the demand requires.

The particular device illustrated in Fig. 19 is peculiarly useful for heating street cars, bath rooms, andother places wherein electric heat is desirable. These different forms have been su gested only as examples of the numerous an diversified uses for which such a device can 'be employed and I do not limit myself either to uses, structures, designs, materials or arrangements exce t as set forth in my several claims which I esire may be construed broadly each independent of limitations contained in other claims.

Having thus described my invention what I claim is:

1. Electric resistance heating device comprising a netted fabric having a warp and weft made, one of naked resistance wire and the other of flexible insulating material, and an imperforate, liquid tight metallic sheathing surrounding said fabric, the insulatlng material portion extending beyond the resistance wire portion and attached to said metallic sheathing.

2. Electric resistance heating device comprising a netted fabric having a warp and weft made, one of naked resistance wire and the other of flexible insulating material, a sheet of previously formed, heat-resisting insulating material covering one face of said fabric, and a metal sheathing surrounding said fabric and insulating material, the other face of said fabric being exposed to said sheathing in heating exchange relation.

3. Electric resistance heating device comprising an imperforate water-tight sheetmetal sheathin a netted fabric therein having a warp an weft one of which contains a naked resistance wire and the other of which is made of flexible insulating material, and elements of insulating material interposed between said sheath and the margins of said fabric.

4. Electric resistance heating device comprising a sheet metal sheathing bent to arcuate form, a netted fabric therein having a warp and weft made, one of resistance Wire and the other of flexible insulating material,

a sheet of flexible insulating material inter: posed between said fabric and the sheathing at one side thereof, and means pressing the sheathing at the other side of said device against a surface to be heated.

5. Electric resistance heating device comprising a sheet metal sheathing bent to arcuate form, a netted fabric therein having a warp and weft made, one of resistance wire and the other of flexible insulating material, a sheet of flexible insulating material interposed between fabric and sheathing, and a flexible backing member overlying said device and pressing its opposite face against a surface to be heated. I

6. The process of making an electric resistance heating element which contains the steps of first making a flexible fabric having a warp and weft composed, one of resistance wire and the other of refractory cord, placing said fabric in company with a preformed sheet of electrically insulating material which is water-free and heat resistant, between sheets of imperforate'sheet-metal, and fastening/rigidly together the adjacent margins of such metal sheets.

7 The process of making electric resistance elements which contains the steps of first weaving a netted fabric having a Warp and woof comprising, one a metallic wire and the other a flexible asbestos containiiig cord, and

afterwards rendering portions of said cord inflexible by wetting the same with a solution condtaining clay, a soluble silicate, and boric ac1 8. The processof making electric resistance elements which contains the steps of first weaving a netted fabric having a warp and woof comprising, one a metallic wire and the other of flexible asbestos cord, afterwards cutting said fabric into sections and wetting the cords adjacent to the place of cutting with a solution containing a soluble silicate where)- by unraveling is prevented.

9. Electric resistance heating element eomv prising a netted fabric having warp and weft comprising, one a naked Wire and the other an asbestos cord, part of said cord being flexible and part being impregnated with a mineral substance which renders it inflexible.

10. The process of producing an electric resistance heating element which contains the steps of first weaving a netted fabric having a 11. The process of making a hermetically sealed electric resistance heating unit of large superficial area which contains the steps of first making a flexible fabric having a warp and weft composed, one of resistance wire and the other of a flexible cord madeof a substance having the herein essential properties of asbestos, placing said fabric, in company with a layer of refractory electrically insulating material, one at each side thereof, between imperforate metal.

sheets, heating such-assembled elements to a suflicient temperature to expel moisture, and afterward hermetically sealing together the edges of said sheets. 3

12; The process of making a hermetically sealed electric resistance heating unit of large superficial area which contains the steps of first making a flexible fabric having a warp and weft composed, one ofresistance wire and the other of a flexible cord made of a substance having the herein essential prop'erill ing said fabric between layers of refractory electrically insulating material between imperforate metal sheets, heating said fabric by passage of an electric current sufficiently toexpel all moisture, and afterwards hermeti- Cally sealing the edges of said sheets.

In testimony whereof I hereunto afiix my signature. EMIL STRANSZKY. 

